Answer:
w =4 ft and l =10 ft
Step-by-step explanation:
Let w = width
l = 2w+2
A = l*w
A = (2w+2)(w)
40 = (2w+2) w
Distribute
40 = 2w^2 +2w
Subtract 40
0 = 2w^2 +2w - 40
Dividing each side by 2
0 = w^2 +w -20
Factor
0 = (w+5) (w-4)
Using the zero product property
w+5 =0 w-4=0
w= -5 w=4
Since we cant have a negative length
w=4
l = 2w+2 = 2(4)+2 = 8+2 =10
